Microwave heating apparatus with a combined food scoop and door

ABSTRACT

A microwave heating chamber (10) has a rectangular opening (12) into which a food support (14) is slidable, the support including a handle (20) and a wall (18) which serves to close and seal the chamber when inserted. The wall (18) may have thermal break (22) with the support to prevent heat being conducted to the wall and handle. The support (14) may have several superposed platforms each to support an item of food, and each may have a rotatable dish.

FIELD OF THE INVENTION

This invention concerns microwave-powered heating devices, and inparticular heating apparatus for heating foodstuffs, more particularlyfor defrosting and heating to a serving temperature frozen pre-cookedfoodstuffs.

BACKGROUND TO THE INVENTION

With the increasing demand for quick, hot snacks and so called "fastfood", there is an increasing requirement to be able to process frozenpre-cooked foodstuffs ready for consumption. In particular, it isnecessary to be able to heat up from the frozen condition a pre-cookedfoodstuff to a serving temperature in the shortest possible time, andtypically a temperature change from -17° C. to +74° C. must be achieved.Preferably the time should be as short as possible, and ideally shouldbe well under one minute.

Conventional microwave ovens are not particularly well suited to thisfunction, and it has been proposed to concentrate the available energyby providing a reflecting surface within a chamber into which microwaveenergy is transmitted so that the latter is focused generally into theregion of the chamber in which the foodstuff is located. In this way theenergy is concentrated into the foodstuff and the latter is raised intemperature at the maximum possible rate.

It is an object of the present invention to provide a more convenientheating chamber for certain foodstuffs.

SUMMARY OF THE INVENTION

According to the present invention there is provided heating apparatuscomprising a heating chamber in which a foodstuff is to be heated usingmicrowave energy; an opening in the chamber wall for giving access tothe interior thereof for the insertion and removal of foodstuffs; and aclosure member therefor which includes a handle on its exterior and afoodstuff supporting platform extending from its internal face, so thatinserting food into the chamber and closing the chamber is effected in asingle operation, the interior of the chamber being formed at least inpart with a concave microwave energy-reflecting surface.

The concave microwave energy-reflecting surface will typically be in theform of a dome. The microwave energy is directed towards the concavesurface to be reflected therefrom and generally focussed towards thefood supporting platform. Other microwave-reflecting geometries may beused to achieve the desired effect.

In one embodiment of the invention, the chamber design is such that atleast some of the microwave energy entering the chamber does not impingedirectly on the foodstuff but can only reach the foodstuff after beingreflected at least once.

According to a preferred feature of the invention the combined closuremember and food supporting platform is in the form of a generally flatscoop of large area which can be slipped below a large area foodstuffsuch as a pizza or pie or quiche, and the large area platform providesthe support for the foodstuff, and the closure is therefore fullyremovable from the chamber in a slidable manner.

Alternatively the closure may be pivotable between a first position, inwhich the food support platform is accessible through the opening in thechamber wall, and a second position in which the closure closes off theopening with the platform inside.

The platform may in this event be in the form of a high-sided tray toprevent foodstuffs from falling thereoff.

According to a further preferred feature of the invention the foodsupporting platform may be formed at least in part from an electricallyconductive material in that in the presence of microwave radiation theplatform becomes heated and assists in the heating-up process and alsoassists in browning the underside of the foodstuff.

In order to prevent the heat in the platform from being conducted away,particularly to the closure and the handle, a thermal break ispreferably provided between the platform and at least the handle, if notalso the closure.

Typically the thermal break comprises a thermal insulating materialcapable of withstanding high temperatures.

Since the browning effect may not be desirable throughout the heatingprocess, the platform may be formed from a microwave transparentmaterial such as glass or ceramic and include an internal cavity intowhich an element of a metallic or other microwave absorbing material canbe inserted during the heating process, either automatically ormanually, to cause the platform to heat up and assist in browning theunderside of the foodstuff.

Where top browning in also required, the chamber may include a secondplatform of glass or ceramic or other microwave transparent materialwith a hollow interior also capable of having an element of microwaveabsorbing material such as metal, metal oxide or metal particles,inserted therein during a heating process.

Two or more platforms one above the other may be provided, eachextending from the internal face of the closure, on which an appropriatenumber of similar foodstuffs, such as pizzas, may be located, thereby tosimplify multiple orders.

Each platform may include a rotatable dish to enable foodstuffs locatedthereon to be rotated within the chamber, to improve the uniformity ofthe heating and browning, where provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference tothe accompanying drawings in which:

FIG. 1 is a perpective view of a microwave heating chamber embodying theinvention and adapted to heat generally flat foodstuffs such as pizzas,and

FIG. 2 is a side view partly in section of the unit shown in FIG. 1,with the closure and food platform inserted.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, a microwave powered heating chamber 10 includes arectangular opening 12 through which food can be inserted into thechamber. A closure is provided in the form of a flat scoop 14 having aplatform for supporting a pizza 16 or the like, having an upstandingwall section 18 which conforms to the opening 12 and just closes andseals same when the scoop 14 has been fully inserted.

A handle 20 is provided by which the scoop can be pushed in and pulledout.

The food-bearing section of the scoop 14 is formed from glass or ceramicor some other microwave-transparent material to prevent it becoming hot.Alternatively, this section of the scoop could be deliberately made froma microwave-absorbing material, deliberately to become hot in acontrolled way, and so to brown or crisp or cook the underside of thefoodstuff. The wall 18 must of course be formed from microwave-opaque ormicrowave-reflecting material such as metal and a thermal break isprovided (if required) at 22 to prevent the transfer of heat from theplatform 14 to the wall 18 and thence to the handle 20.

FIG. 2 shows the scoop 14 fully inserted into the heating chamber 10.Below the platform of the scoop is a microwave source 23 (not shown)such as a magnetron and the inside of the domed region of the chamber isformed from, or coated with microwave reflecting material such as metalso that energy incident thereon is reflected and focussed back towardsthe foodstuff 16.

A power supply may be located within the housing 10 or in the line as at24.

We claim:
 1. A microwave-powered heating apparatus comprising a heatingchamber formed internally with a concave surface for reflectingmicrowave energy; a microwave source for directing microwave energy intothe chamber; an opening formed in the chamber to enable insertion andremoval of foodstuff to be heated; and a fully removable closure memberfor closing said opening and having a substantially horizontal platformfor supporting foodstuff, said platform being generally in the form of aflat scoop onto which can be slipped a foodstuff of relatively largearea, whereby the insertion of the foodstuff into the chamber and theclosing of said opening is effected in a single operation.
 2. Apparatusaccording to claim 1, wherein the concave reflecting surface is in theform of a dome.
 3. Apparatus according to claim 1, in which the chamberdesign is such that at least some of the microwave energy entering thechamber does not impinge directly on the foodstuff but can only reachthe foodstuff after being reflected from said concave surface. 4.Apparatus according to claim 1 in which the food supporting platform isformed at least in part from an electrically conductive material, sothat in the presence of microwave radiation the platform becomes heatedand assists in the heating-up process and also assists in browning theunderside of the foodstuff.
 5. Apparatus according to claim 4 in whichsaid closure member comprises an external handle, and in which a thermalbreak is provided between the platform and the handle.
 6. Apparatusaccording to claim 5 in which the thermal break comprises a thermalinsulating material capable of withstanding high temperatures.